1. Field of the Invention
The present invention is related to processing systems and processors, and more specifically to techniques for managing values of hardware thread specific information returned to logical partitions executed by hardware threads of a processor core.
2. Description of Related Art
In large scale computer systems, in particular in multi-user computer systems or so-called cloud computing systems in which multiple processors support multiple virtual operating systems and images, referred to as logical partitions (LPARs), a hypervisor manages allocation of resources to the LPARs, and the starting/stopping of LPARs at system startup/shutdown and context swaps. The LPARs are preferably isolated from each other when the system is used, for example, to support execution of different LPARs for different customers. Typically, the processor cores used in such a computer system support concurrent execution of multiple hardware threads, e.g., 8 or more hardware threads, which correspond to parallel execution pipelines within the processor core. Typically also, the hypervisor assigns a number of threads to each LPAR.
Status and other informational values within the processor are hardware thread-specific, i.e., the values may be either a value for each hardware thread number, be dependent on the thread trying to access the value, or may be the number of hardware threads that the processor supports.
It would be desirable to provide techniques for managing accesses to hardware thread-specific information that are independent of which LPAR is accessing the information and provides security between LPARS.